I was an officer in our aviation club at my college, and we arranged a tour of the tower and TRACON facility in Spokane, Washington fairly easily. We got to see both the tower and TRACON with no trouble at all. Also, we arranged a tour of Seattle Center fairly easily as well. We never took the tour due to scheduling issues with our club, not the center, but if I remember right, the only stipulation we had is that they could only take a certain number of people at once, but it wasn't difficult at all.